1. Field of the Invention
The present invention relates to shrimp peeling devices, and more particularly to a method and apparatus for peeling shrimp that includes alternating larger diameter rollers and smaller diameter insert rollers positioned side-by-side and wherein an improved roller hold down device loads the smaller diameter insert rollers into contact with the larger diameter rollers with an improved configuration and geometry that enhances efficiency, minimizes shrimp damaged during peeling, and affords flexibility when shrimp vary in grade and type.
2. General Background of the Invention
In about 1947, Fernand S. Lapeyre and James M. Lapeyre were faced with the problem of peeling shrimp with a mechanized peeler. The shrimp peeler that they invented made it no longer necessary to rely upon hand labor to sort, peel, or clean shrimp. Early patents that relate to these Lapeyre shrimp peelers include U.S. Pat. Nos. 2,637,065; 2,537,355; 2,574,044; and 2,429,828.
An example of these early patents is the Lapeyre Patent 2,537,355 entitled "Machine For Peeling Shrimp". The '355 patent discloses a machine for peeling shrimp that includes a channel through which the shrimp are adapted to move comprising a base roller and two spaced channel rollers above and in contact with opposite side portions of the base roller to provide a nip running longitudinally at each side of the channel. Means are provided on the machine to impart an oscillatory motion to the base roller to move the shrimp in the channel from one side nip to the other.
The Lapeyre Patent 2,778,055 discloses a machine for peeling shrimp that includes a bottom roller on the machine, parallel side rollers on the machine disposed on opposite sides of the bottom roller and spaced therefrom, and elevated therefrom to form a peeling channel with the bottom roller for the shrimp. Insert rollers are operatively associated with the machine and positioned between the bottom and side rollers. A hold down arrangement is provided for the insert rollers that is operatively associated with the bottom and side rollers exending movably down through the spaces between the bottoma nd side rollers having a resilient connection to the machine. The '055 patent names Fernand Lapeyre, James Lapeyre, and Emile Lapeyre as inventors.
U.S. Pat. No. 3,070,832, entitled "Pressure Finger Loading Device For A Shrimp Peeling Machine", names Fernand S. Lapeyre as inventor. The '832 patent relates to a pressure finger loading device for a shrimp peeling machine and has for an object to provide means for loading differentially or equally and simultaneously all of the pressure fingers carried in a pressure-finger frame such as the pressure finger frame illustrated in U.S. Pat. No. 2,778,055.
An apparatus for peeling pre-cooked shrimp is the subject of U.S. Pat. No. 3,383,734, issued for James M. Lapeyre. The '734 patent includes a first peeling section having members forming peeling nips positioned to receive shrimp hot from a cooker. The first peeling section has pressure means for urging the shrimp into contact with said members forming said peeling nips. A second peeling section is positioned to receive shrimp from the discharge end of the first peeling section. The second peeling section has peeling nips defined by members having different coefficients of friction between themselves and the second peeling section being devoid of any pressure means for urging the shrimp into contact with the members forming the peeling nips. The second peeling section is up to one-half the length the first peeling section.
A drive mechanism for a shrimp peeling machine is disclosed in U.S. Pat. No. 3,626,551, issued to James M. Lapeyre. The '551 patent is directed to driving the peeling rollers of a shrimp peeling machine and the pressure finger frames mounted thereover by a pitman arm actuated bell crank, which rocks on a cam shaft or a pair of cam shafts which raises and lowers the pressure finger frame and simultaneously drives the peeling rollers.
U.S. Pat. No. 3,706,113 provides a shrimp peeling machine that is directed to hold down devices for insert rolls on shrimp peeling machines and embodies an upright member subject to being spring loaded at its base and carrying a cross beam member proximate its top which is retained in a loose fit by a plastic filler material which will permit the cross beam to rock relative to an upright member. Each end of the cross beam member is hooked downwardly to pass through and restrain insert roll hold down straps.
U.S. Pat. No. 3,740,795, issued to James Cox and entitled "Seafood Peeler Using Rollers Of An Endless Conveyor And A Bank Of Inclined Rollers" discloses a machine that peels seafood such as shrimp. The seafood is delivered to rollers. When the contacting surface between the rollers moves downward, they draw the shell through the reject the slippery meat. On the reverse movement of the surfaces, the rejected meat is carried over the second roller to the next.
U.S. Pat. No. 3,816,877, issued to Kenneth Bullock, discloses a shrimp cleaning machine. The '877 patent is directed to cleaning marine life such as shrimp by passing the shrimp down between spaced peeling rolls and having a vertically reciprocating plate therebetween with the rolls on movable centers positioned as a function of the plate shape and position, with the plate having shaped sides with a traveling belt moving over the top edge of the plate for carrying away the cleaned shrimp. The rolls have an outer surface of a predetermined hardness and material rotating at a predetermined speed with the plate vertically reciprocating at a predetermined speed and a spray provided for cleaning the rolls and plate and forcing uncleaned shrimp into the nips between the rolls and plate.
U.S. Pat. No. 3,971,102, issued to Skrmetta, discloses a roller for shrimp peeling machines that include a gapped portion along its length, for example at its upper end, to effectively shorten the effective peeling section of the machine without substantial modification of the basic machine itself by allowing the shrimp to fall through the gapped portion rather than traversing the full length of the roller. The gapped rollers are substituted for the standard peeling rollers which provide peeling action along their full length, when a shorter peeling section is desired. Several different gapped rollers are disclosed, some reversible end-for-end and others forming a series of subsequently related rollers which have a varying location of the gap portion along the roller length.
U.S. Pat. No. 3,975,797, issued to Grames et al., is directed to a shrimp processing apparatus. In the '797 patent, cooked shrimp to be peeled are distributed successively to tiers of sets of peeler rolls and cooperative reciprocative bars. The apparatus is said to permit coordinated adjustments of nip spacing and taper angle in the roll-bar tiers independently at corresponding ends of the sets and in each tier independently of the other to permit optimum shucking in the first tier and polishing in the second tier suited to type and condition of shrimp. Cams are engaged by cam follower rollers connected to the peeler rolls to control nip distance between the bar and rolls at both ends as a function of relative vertical positioning of each bar and its associated peeler rolls.
The Dell Patent 4,400,849 discloses a shrimp peeling unit that features a pair of journaled generally horizontal and parallel side-by-side rollers including at least closely adjacent sides defining an elongated upwardly opening "nip" area therebetween. Structure is provided for supplying successive shrimp to be peeled to one end of the "nip" area and drive structure is operatively connected to the rollers for inversely oscillating the latter. The drive structure includes adjustment features operative to adjust the angular extent of oscillation of the rollers, the phase change speed of oscillation of the rollers and the cycle frequency of oscillation of the rollers. Further, a row of fingers are mounted for adjustable speed movement along the "nip" area and are engageable with the shrimp within the "nip" area for urging the shrimp therealong and spray heads are arranged along the "nip" area for directing spray jets of liquid into the "nip" area for assisting in the removal of the shells of the shrimp and also the cleaning of the shrimp being peeled or shelled.
In the Griffis Patent 5,005,258, a plurality of shucked shellfish are mechanically eviscerated utilizing a series of longitudinally aligned inclined channels, each channel formed of a power-driven roller and adjacent insert rollers. The insert rollers extend generally parallel and longitudinally and are aligned with each other. The frictional surfaces of the rollers and the spacing between the adjacent rollers, or both, are controlled to effectively separate the soft shellfish viscera from the soft adductor muscle of the shellfish without significant damage to the muscles.
U.S. Pat. No. 5,108,342, issued to George Lapeyre, Brent Ledet, and James E. Saul, Jr., is entitled "High Yield Peeling Means And Method for Uncooked Warm-Water Shrimp". The '342 patent discloses improved machinery and methods for peeling raw, warm-water shrimp to solve the prior art problems of scarring of the shrimp meat and removing of an excess of the edible meat. A critical nip angle of between about 21.degree. and 33.degree. is produced by an insert nip-forming roller having a smaller diameter than conventionally used in the prior art, to considerably improve shrimp appearance while increasing the yield of shrimp meat. Attention is also given to the length and surface configuration of the insert rollers. With at least three axially aligned insert sections, better roller support prevents bowing and lengthens life. Selection of different axially disposed surface configurations permits special-purpose treatment of shrimp. For example, initial removal of waste is expedited by knurled surface sections, and final treatment by smoother sections prevents disfiguration of the peeled shrimp meat.
In the Ledet Patent 5,120,265, there is disclosed an apparatus and method for improving the yield of peeled shrimp meat obtained with roller-type peeling machinery. In the '265 patent, the yield increase is achieved by means of critical interacting operating relationships in the peeling action between power rollers, intermediate rollers, and insert rollers, expressed in terms of relative roller diameters. Preferred sets of rollers are identified that significantly increase the yields of cold water Pandalus species of shrimp in sizes of 90/kg to 350/kg over conventional commercial rollers. The high throughput quantity of the peelers is not seriously compromised and may be even increased by the ability to provide more peeling channels in a conventional size peeling tray by replacement with smaller diameter power rollers. The preferred roller sets for use in current standard commercial equipment, without other changes, has lower power rollers of 2.5 inch (6.4 cm) diameter, intermediate upper channel forming rollers of 2 inch (5 cm) diameter and insert rollers of 7/16 inch (1.1 cm) diameter. The method of establishing critical roller diameters provided by this invention permits adaption of the feature of obtaining highest yields feasible with critical roller diameter selections for various conditions encountered in the shrimp peeling industry or at a particular peeling site, including product variations from different shrimp catches, sizes, species, etc.
U.S. Pat. No. 5,346,424, issued to Chiu et al., discloses an automatic size-grading and shrimp peeling machine for shrimp. The automatic grading machine includes a plate-partition conveyor mounted to a slanting platform. The slanting platform is mounted with at least three conveying screw shafts coupled with the plate-partition conveyor and a plurality of feeding pipes of peeling machine. The automatic grading machine is mounted on a machine supporting frame so as to have all feeding ports mounted over the peeling machine, which includes at least three peeling units. Each unit includes a large swing peeling roller and two small revolving peeling rollers; a pressing roller and at least one squeezing wheel are mounted between two small revolving peeling rollers. The squeezing wheel and the pressing roller are mounted parallel to each other, but perpendicular to the small revolving peeling rollers.